Detonating fuse



Dec. 6, 1927. v 1,651,696

N. GREENWELL K DETONAMNG FUSE Filed Sept. 2'7, 1924 2 Sheets-Sheet 1 l? l? /wg f `.f/f. "l f 4- BY f.

ATTORNEY Dec. 6, 1927. 1,651,696

N. GREENWELL DETONATING FUSE Filed Sept. 27. 1924 2 Sheets-Sheet 2 i W. J.

lll/ll' INVENTOR BY ffl@ ATTORNEY Patented Dec. 6, 1927.

UNITED STATES PATENT OFFICE I enrENWELL,V or BETHLEHEM, PENNSYLVANIA,I `AssIeNoa 'ro BETHLEHEM STEEL COMPANY.

DETNATING FUSE.

The invention relates to detonatingv fuses for projectiles and it comprises means for insuring safety in handling the fused projectile and insuring the explosion of the projectile at the proper moment when fired.

It should be understood that the high eX- plosive constituting the bursting charge of projectiles is more or less inert under normal conditions and in order to obtain a complete explosion it is necessary to provide a powerl Y ful detonating medium imbedded in the charge to initiate the explosion thereof. There are several well known substances which are suitable for this purpose and of these substances, fulminate of mercury, is

the most common in use. However. this latter substance isvery sensitive to shock and the quantity which may be used with safety is limited. To cause the complete explosion of a charge of a large calibre projectile, a comparatively large detonating element is required and the use of fulminate-of mercury alone would be prohibitive. It is well known that when a column of this substance exceeds certain proportions the shock occasioned by the discharge of the projectile from the gun is suicient to cause the detonation thereof due to the inertia of the column of powder itself. To overcome this '30 danger a less sensitive explosive is interposed between the detonator and the projectile charge proper. The intermediate eXplosive substance whileV less sensitive than the detonating material used is, however, of a much higher order of explosive than the material comprising the main charge of the projectile and serves to boost the wave of detonation from the detonating element and thereby effect a complete explosion of the 40 charge. Even though the size of the detonating element is reduced to a minimum suiiicient to secure a high order detonation of the booster charge there is a certainelement of danger in handling or due to shock occasioned by discharge of the projectile from the gun causing a premature explosion. To avoid this danger it is usual to have the detonating element placed in a chamber separate from the booster element of the fuse '5U in such a manner that a premature eXplo-` employ in a fuse an extension spring, operated by vthe inertia of a movable member when the projectile is fired, to effect the movement of a detonator element of a fuse from its safety position into its active position within the booster charge.

VA further object is to provide a `device comprising an inertia member securely connected to one end of an extension spring, an anchoring means securely connected to the other end of the spring, said parts constituting a unitary structure which may be easily assembled in place in a fuse in assured correct relation to the coacting parts comprising the fuse mechanism.

There are several known devices adapted to bring the. `detona-ting element into communication with the booster element after the projectile has been discharged from the gun vand the acceleration of the projectile has ceased. Of these devices the most sat-isfactory are-those which employ a compression spring to operateduring the flight of the projectile and move the detonator .element to its forward position within a pocket formed in .the booster charge.` However, the use ofcompression springs hitherto practiced for the purpose of effecting the movement of the detonator is unsatisfactory and unreliable, and particularly springs assembled in their compressed state. `Compressed springs are disposed rearwardly of the detonating element and tend to urge the latter into its forward position but is prevented from this movement by means made inactive when the projectile is discharged from the gun. The'preferred means adopted for this purpose are centrifugal devices which serve the dual purpose of restraining the movement of the detonating element and at the same time function as a closure to the passage communicating the safety chamber and the booster charge. Unless due precaution is taken the pressure of said compression spring against the centrifugal device will prevent the operation of the latter and thus hinder the successful operation of the fuse."

Devices have hitherto been practiced which employ a' compression spring positioned behind an inertia operated member and compressed by the latter when the projectile is discharged from the gun. Means are also provided to operatively connect said member to the detonator whereby the latter is moved forward after the acceleration of the pro- Y jectile has ceased. VVViththe latter type of' device difficulty is encounteredwhen assembling the parts, particularly in quantityproduction, so.,,that each part is operatively 'positioned with reference to the other. '.ffur-,rY thermore, the sudden load imposed upon the compression springcauses the coils to buckle,

and distort and interfere with the correct functioning ofthe inertia member.

The present invention comprises generally 'aproj ectilefusecontaining a booster lcharge and having. a detonatoi' element norm'allydisposed vin a safety chamber and separated from said charge by means of a centrifugallyoperated shutter, an inertia member slidably mounted in the safety chamber and` restrained against rearwardv movement by j means of an extension spring anchored at 'one end to the body of the fuse and secured 4at the other end tothe .inertia member, and means whereby the latter member is operably connected to the detonator' when moved to itsY rearinostposition atz the discharge; of the it assumes'when the projectile has-moved "a certain distance along the'bore of the gun; A Fig. 3 is similar toV Fig. 1, Ashowing the various parts inthe armed condition which itiassumes during thei'light; and, y Fig. 4t is across sectional. view fonfthe lines IV-IV' of Fig. 3. f i f i "Referring to the drawings, 10y indicates the body of the fusewhich is of the ordinary cylindrical form and-threaded to. engage -a threaded Opening centrally" located in" .the

' base of a projectile.y Thefusebodyl is hol# low, being closed at the rear end by a heavy cylindrical base .11 and at the `forward end `by a screw plug 12. Threaded into the in. Aterior of the fuse toward the rear end of the cavity is a plug 13, which is bored from its front face to provide a` seat fora block 14.

AThe 'latter is retained in place by a plug -15 threaded in thefplug 13.] The front faceof the plug 1A5is `centrally `b'oredand recessed to receivea primer 16 which is supported by thegblock '14.v The latter has a transverse perforation 1T which contains a delay pellet operating as .a timing element and; communicates with the primer through theflasli ports 18. vAfpassage 19 permits'communica-- tion for iirefrorn the delay'pellet to pass to a magazine vcharge 20 between the block, 14.

and theibottom ofthe-plug 13. l ,The plug'l3 has a central passage 21 tlirougliwhich the lasli from the. magazine charge passes for a purpose to be presently explained. In-

tegralwiththe plug 13 is a reinforcing cylf inder 22 "extending forwardly within" the l fuse body and is provided .with an end flange fitting the interiorwall of said body. Atthe forward end of the cylinder 22 is a fixed disc 28Vwhich has a centralopening to allow for the passage of a detonator hereiuafterdescribed. Theportlon of the fuse lbetween the vplug 13 and the disc 23 constitutes a stron 'safety chamber reinforced by the walls o' the cylinder 22 tohousesaid detonator in its inactiveposition.

The disc 23 is-provided with radial cavities in which arel spring pressed bolts 24`which normally extend into the. aforesaidI central j opening in the disc and prevent the passage of the detonator but which move'outward during the'iiightofthe projectile under the action vof fcentrifugal force. Centrally lo` cated inthefuse cavity and surrounded by lthe cylinder 22ris a Vdetonator 25fcomprisinga tube of relative small diameter {ille-dV witha detonating composition. `The rear end of-the detonator is threaded into a detonator 'holder 26 which is lseated-'in the passage 21. The detonator i holder 'has a tubular opening in line with the passage 21 o through vwhich fire may pass to ignite the composition in the tube.. Al cannelure-groove is vformed on the exterior of the holder 26 and retains a springshoulder 27 for the purpose now to be described.

.An annular plate 28fis gripped between the disc 23 vandthe cylinder 22 and has an annular groove formed in the face thereof to receive the end coil of an extension spring 29,; which isthreaded into position throughV an Vaperture in the plate providedfor the purpose. yThe end` ofthe spring is bent inwardly at rightangles to constitute a detent which snaps intopapoclret. formed' in the plate 28. An. inertia member 30 is slidingly mounted in "the interior-of the cylinder 22 and is centrally bored to .slide overthe fdetonator holder asfillustrated in Fig. 2. Y A

recessie formedin-,the face of the member 30 to receive th'eextcnsion spring 29, thezend Vcoil of,v which is threaded throughan apern ture .in the' bottom wall .of saidinember van d securely locked in placeina similarrnanner as that employed to secure the opposite end coilof the spring to the plate 28.vr The inertiameinber- 30 y.is grooved internally andV the central bore is flared outward'as indi-` catedon the drawings. When the projectile isfired from av'gun, tlieinertia of the ineinber .30r causes relative longitudinal movement between said member and the 4detonater holder,= restrained .by z'the extension spring 273 and the parts assume the position as shown in Fig..2 r.ly The spring' shoulder 27 `is conipressed bythe 4passage of` the yinertia member nog over the holder 26 and is reduced in diameter, however, when the aforementioned grooves in said member and holder register, the spring shoulder 27k returns to its original condition and thereby locks the parts together.

In the chamber at the rear of the primer 15 there is arranged a. percussion plunger having a firing pin, which is adapted to be moved forward and tire the primer when the projectile is suddenly retarded in flight. This percussion device may be of any suitable form such for instance, as that shown in Patent No, 1,397,855, dated November 22, 19214 As illustrated in' the dra-wing it coinprisesl a cylindrical hammer body 31 on which is fixed an axially arranged firing pin 32, the point of which extends forward of the body. Surrounding the firing pin at its forward end is a cylindrical guard 33 which is normally located in its forward position Vwith its front surface flush with or forward of the firing pin point and held in this position by centrifugal bolts 34 which are normally pressed into Contact with the firing pin by springs. Vhen these bolts are in their normal position as shown in Fig. 1,

.they prevent rearward movement of the Yso tube. Y plodes the booster charge which ruptures the guard 33. The bolts 34 operate in radial openings in the hammer body and the guard is free to move rearwardly in an axial opening in the hammer body when the bolts are withdrawn.

In the chamber coniined-V between the disc 23 and the plug 12 there is a booster charge of explosive material 35 having a central cavity 36 adapted to receive the detonator 25 when the latter is in its forward position as shown in Fig. 3. The forward end of the detonator tube is of thicker metal than the balance of the tube and has a tapering wall 37 provided with a conical cavity in which there is a cone plug 38 for a purpose to be presently explained.

- The operation is as follows: When the projectile is fired the member 30 moves relativelyv rearward under its inert-ia, restrained by t-he spring 29, passes over the detonator Vholder 26 and is locked therewith by means of the spring shoulder 27 as heretofore described. The rotary movement of the projectile throws out the bolts 24, and when acceleration ceases, permits the spring 29 to move the detonator into the cavity 36 in the booster charge. The bolts 34 in the percussion plunger are also thrown out permitting the rearward movement of the guard 33 on impact, The fuse is thus armed and on impact the firing pin strikes the primer and ignites the delay pellet which in turn, after apredetermined interval of time, ignites the magazine charge 20 and the flame from the charge ignites the material in the detonator This immediately detonates and exfuse and detonates `the bursting charge of the projectile.

The operation of the safety devices embodying the fuse is as follows: The firing pin point is normally within the boundary of the guard member and it cannot strike the primer if, forany reason, the plunger should move forward accidentally. If, in anyway, the detonator 25 should be accidentally eX- ploded during handling the projectile or due to shock of discharge while in the gun, the explosion would drive the tapered gas plug 38 into the tapering end of the detonator tube spreading the latter and make it fit tight the opening in the disc 23. The end of the detonator tube would be prevented from being blown forward by the bolts24, the expanded gases not having strength sufficient vto burst the walls of the body 10 reinforced by the cylinder 22. It will thus be seen that while the described fuse -is practically certain of operation when fired, it is provided with a safety device which makes it practically impossible for the booster charge to be detonated prematurely.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

1 'In a fuse for projectiles, the combination with a hollow fuse body, of a booster charge in the forward part of the fuse formed with a receptacle for a detonator, a detonator normally in the rear of the booster charge Aand a disc in the rear of the booster charge having an opening through which the detonator may pass, means adapted to be made inactive under centrifugal force for normally holding` said detonator in place, an inertia member surrounding the detonator normally disconnected therefrom and adapted to bc connected thereto when the projectile is discharged from the gun, a spring interposed between said inertia member and said disc, means to anchor one end of said spring to said inertia member, and means to anchor the other end of said spring to said disc.

2. In a fuse for projectiles, the combination with a hollow fuse body, of a booster charge in the forward part of the fuse formed vwith a receptable for a detonator. a safety chamber in the rear of said booster charge, a wall between the latter and the safety chamber having a central opening coaxial with said receptacle, a detonator loosely mounted in the safety chamber and supported in said opening at one en'd, an inertia member slidingly mounted in the safety chamber and resiliently connected to the fuse body, a resilient member mounted on the detonator adapted to engage said inertia member when the projectile is fired from a gun, and means made inactive by the rotation of the projectile for preventing the passage of the detonator through said central open- 'ing into the charge.

v3. InV a fuse for projectiles, the combinaf` tion with al hollow fuse body, divided into a plurality of chambers by Wallsof substantial thickness, of a booster charge in the Aforward chamber of the fuse formed with la receptacle fora detonator, a percussion device located in the rear chamber ofthe fuse, a detonator loosely mounted in the intermediate chamber of the fuse, a primer mounted in the wall separating the last mentioned chambers.y conduits adaptedl toconvey the flash from the primer to the detonator, a central opening in the 'Wall between the intermediate cha1n.

ber and said booster charge, means mounted in the latter Wall adapted to normally prevent the passage of the detonator into said receptacle and to become inactive when the projectile rotates, an inertia member slidingly mounted in the safety chamber,'an eX- tension spring intermediate said inertia member and the-end Wall of said chamber,

receptacle ,formed in the booster means to a1ichor,one end of saidzspringy to said end Wall, means to vanchor the other A'end ot said'spring to said inertia member, and meanstoestablish a connection between the detonator and the inertia. member on shock j of discharge of the project-ile from the gun.

.4. Ina fuse for projectiles,-the combination of a fuse body having a safety chamber,

of a' detonator mounted in said chamber, an n inertia member mounted in said chamber normally disconnected from vthe detonator,

.an extension spring intermediate the inertia membeiyrand the end wall-of said chamber, means to anchor one end of said spring tov said end Wall, means to anchor the other 'il end of said spring to said inertia member,

projectile is 'A 

